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    <title>等腰三角形</title>
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        .box {
            margin: 70px auto;
            box-sizing: border-box;
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            height: 400px;
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            border-right: 79px solid;
            border-bottom: 200px solid;
            border-left: 200px solid;
            border-color: transparent red transparent transparent;
            transform: rotate(-159deg);
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